Limits...
Redundancy and modularity in membrane-associated dissimilatory nitrate reduction in Bacillus.

Heylen K, Keltjens J - Front Microbiol (2012)

Bottom Line: The genomes of two phenotypically denitrifying type strains of the genus Bacillus were sequenced and the pathways for dissimilatory nitrate reduction were reconstructed.In addition to the already characterized menaquinol/cyt c-dependent nitric oxide reductase (Suharti et al., 2001, 2004) of which the encoding genes could be identified now, evidence for another novel nitric oxide reductase (NOR) was found.Also, our analyses confirm earlier findings on branched electron transfer with both menaquinol and cytochrome c as reductants.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Microbiology, Department of Biochemistry and Microbiology, University of Ghent Gent, Belgium.

ABSTRACT
The genomes of two phenotypically denitrifying type strains of the genus Bacillus were sequenced and the pathways for dissimilatory nitrate reduction were reconstructed. Results suggest that denitrification proceeds in the periplasmic space and in an analogous fashion as in Gram-negative organisms, yet with the participation of proteins that tend to be membrane-bound or membrane-associated. A considerable degree of functional redundancy was observed with marked differences between B. azotoformans LMG 9581(T) and B. bataviensis LMG 21833(T). In addition to the already characterized menaquinol/cyt c-dependent nitric oxide reductase (Suharti et al., 2001, 2004) of which the encoding genes could be identified now, evidence for another novel nitric oxide reductase (NOR) was found. Also, our analyses confirm earlier findings on branched electron transfer with both menaquinol and cytochrome c as reductants. Quite unexpectedly, both bacilli have the disposal of two parallel pathways for nitrite reduction enabling a life style as a denitrifier and as an ammonifying bacterium.

No MeSH data available.


Physical map of the B. azotoformans LMG 9581T and B. bataviensis LMG 21833Tnar (A) and nap (B) gene clusters. Arrows show the direction of transcription. Open reading frames are drawn to scale. Homologous genes are shown in identical colors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3475470&req=5

Figure 1: Physical map of the B. azotoformans LMG 9581T and B. bataviensis LMG 21833Tnar (A) and nap (B) gene clusters. Arrows show the direction of transcription. Open reading frames are drawn to scale. Homologous genes are shown in identical colors.

Mentions: The reduction of nitrate to nitrite in Bacteria is catalyzed by three different types of enzymes, that all bind a molybdenum bis molybdopterin guanine dinucleotide (Mo-bis-MGD) cofactor at the catalytic subunit together with a 4Fe-4S cluster for electron transfer (Rothery et al., 2008). Two of these nitrate reductases (NARs) are involved in respiration, the cytoplasmic Nar, and the periplasmic Nap. The third one, Nas, acts in nitrogen assimilation and is localized in the cytoplasm. In the genome of B. azotoformans a gene coding for Nas is absent, but the organism contains the inventory for two functional Nar systems as well as one Nap protein complex (Figure 1). As yet, the presence of a periplasmic NAR has not been reported for a Gram-positive bacterium.


Redundancy and modularity in membrane-associated dissimilatory nitrate reduction in Bacillus.

Heylen K, Keltjens J - Front Microbiol (2012)

Physical map of the B. azotoformans LMG 9581T and B. bataviensis LMG 21833Tnar (A) and nap (B) gene clusters. Arrows show the direction of transcription. Open reading frames are drawn to scale. Homologous genes are shown in identical colors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475470&req=5

Figure 1: Physical map of the B. azotoformans LMG 9581T and B. bataviensis LMG 21833Tnar (A) and nap (B) gene clusters. Arrows show the direction of transcription. Open reading frames are drawn to scale. Homologous genes are shown in identical colors.
Mentions: The reduction of nitrate to nitrite in Bacteria is catalyzed by three different types of enzymes, that all bind a molybdenum bis molybdopterin guanine dinucleotide (Mo-bis-MGD) cofactor at the catalytic subunit together with a 4Fe-4S cluster for electron transfer (Rothery et al., 2008). Two of these nitrate reductases (NARs) are involved in respiration, the cytoplasmic Nar, and the periplasmic Nap. The third one, Nas, acts in nitrogen assimilation and is localized in the cytoplasm. In the genome of B. azotoformans a gene coding for Nas is absent, but the organism contains the inventory for two functional Nar systems as well as one Nap protein complex (Figure 1). As yet, the presence of a periplasmic NAR has not been reported for a Gram-positive bacterium.

Bottom Line: The genomes of two phenotypically denitrifying type strains of the genus Bacillus were sequenced and the pathways for dissimilatory nitrate reduction were reconstructed.In addition to the already characterized menaquinol/cyt c-dependent nitric oxide reductase (Suharti et al., 2001, 2004) of which the encoding genes could be identified now, evidence for another novel nitric oxide reductase (NOR) was found.Also, our analyses confirm earlier findings on branched electron transfer with both menaquinol and cytochrome c as reductants.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Microbiology, Department of Biochemistry and Microbiology, University of Ghent Gent, Belgium.

ABSTRACT
The genomes of two phenotypically denitrifying type strains of the genus Bacillus were sequenced and the pathways for dissimilatory nitrate reduction were reconstructed. Results suggest that denitrification proceeds in the periplasmic space and in an analogous fashion as in Gram-negative organisms, yet with the participation of proteins that tend to be membrane-bound or membrane-associated. A considerable degree of functional redundancy was observed with marked differences between B. azotoformans LMG 9581(T) and B. bataviensis LMG 21833(T). In addition to the already characterized menaquinol/cyt c-dependent nitric oxide reductase (Suharti et al., 2001, 2004) of which the encoding genes could be identified now, evidence for another novel nitric oxide reductase (NOR) was found. Also, our analyses confirm earlier findings on branched electron transfer with both menaquinol and cytochrome c as reductants. Quite unexpectedly, both bacilli have the disposal of two parallel pathways for nitrite reduction enabling a life style as a denitrifier and as an ammonifying bacterium.

No MeSH data available.